Tens of thousands of pieces of space junk are orbiting our planet – from defunct satellites to flakes of paint – putting working satellites at risk. Here are three potential solutions
What goes up doesn’t always come down in the case of space junk. Tens of thousands of pieces of rubbish remain in orbit, but it’s not just the volume of debris that poses a potential problem to functioning spacecraft – it’s the speed at which it is travelling.
Zipping about in the low orbit at upwards of 22,000mph, even something as small as a bolt can do serious damage to satellites upon which we depend for things like communication.
“Imagine how dangerous sailing the high seas would be if all the ships ever lost in history were still drifting on top of the water,” said Jan Wörner, director general of the European Space Agency, highlighting the problem. “That is the current situation in orbit, and it cannot be allowed to continue.”
Here are three smart solutions to the problem of space junk.
One of the less madcap, more prosaic, solutions to space junk is the Space Sustainability Rating (SSR) system. Unveiled last week by the European Space Agency (ESA) and World Economic Forum, it promises to bring some order to the ‘wild west’ of space, and ensure that future missions mitigate the chances of generating yet more orbital litter.
From early 2022, spacecraft operators will be able to have their expeditions accredited by the SSR. The system will give a peer-reviewed assessment of each mission, based on factors including choice of orbit, measures taken to avoid collisions and plans to de-orbit satellites on completion of the mission.
The accreditation system is voluntary, but supporters hope that it will create a race to the top for space actors.
Holger Krag, from the ESA, which helped develop the system, said: “The SSR aims to influence behaviour by all spaceflight actors, especially commercial entities, and help bring into common usage the sustainable practices that we desperately require.”
Preventing more space junk from entering orbit is just part of the solution – retrieving existing debris is also vital. Enter ClearSpace-1, which will be the first space mission to remove an item of rubbish from orbit.
Due to launch in 2025, the mission will aim to capture a 100kg payload adaptor that sent the ESA’s Proba-V satellite (pictured) into space. It is now surplus to requirements and swirling around with tens of thousands of other pieces of space junk.
The pioneering mission to remove the item is being led by the Swiss startup ClearSpace. The hope is that it will demonstrate the potential for new junk-removal spacecraft and create a market for space rubbish clearance.
“Even if all space launches were halted tomorrow, projections show that the overall orbital debris population will continue to grow, as collisions between items generate fresh debris in a cascade effect,” said Luisa Innocenti, head of the ESA’s Clean Space initiative. “The only way to stabilise the orbital environment is to actively remove large debris items.”
Image: The Proba-V satelite sits atop its payload adaptor. Credit: ESA
A Japanese company and Kyoto University have joined forces to develop what they hope will be the world’s first satellites made partially out of wood. Set to launch in 2023 with completion targeted for 2030, the shell of the LignoSat satellite will be made from timber, allowing it to burn up completely as it re-enters the Earth’s atmosphere.
The project aims to avoid adding to the estimated 2,550 defunct satellites that are currently in orbit despite being surplus to requirements.
“We are very concerned with the fact that all the satellites that re-enter the Earth’s atmosphere burn and create tiny alumina particles, which will float in the upper atmosphere for many years,” Takao Doi, a professor at Kyoto University and Japanese astronaut, told the BBC.
The wooden satellites would burn up without releasing junk into space or showering debris on the ground as they fall down to Earth.
Image: Sumitomo Forestry/Nikken Sekkei
Main image: Nasa